H.C. (Hydro Carbon)
The interest in the use of hydrocarbon refrigerants (HC), as well as for all other natural refrigerants (eg ammonia, carbon dioxide), originated from when it was discovered that the CFC and HCFC fluids are bad for ozone air while HFCs contribute quite significantly to the greenhouse effect. Otherwise, the use of natural refrigerants not entail problems for the environment.
They do not contain chlorine or fluorine, being composed of carbon and hydrogen. Hence their progressive success not only as a working fluid in refrigeration systems. However the flammability is the big rock that did not allow these fluids to be accepted universally in the market. In favor, however, the use of HC, certainly play the good heat transport properties (that requires refrigerant reduced loads) and the possibility of use of mineral type oils, which allows to avoid the problems related to the humidity due to use of sintetic lubricants.